iio: dac: ad5758: Add support for hard reset

The ad5758 has a hardware reset active low input pin. This patch adds a
devicetree entry for a reset GPIO and a new ad5758_reset() function.
During
initialization, it is checked if the reset property is specified and the
the GPIO is being asserted, therefore the device will become active.

When the reset function is called, if the gpio_reset var is set, then
the
GPIO will be toggled, otherwise a software reset is performed.

Signed-off-by: Stefan Popa <stefan.popa@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/iio/dac/ad5758.txt b/Documentation/devicetree/bindings/iio/dac/ad5758.txt
index bba01a5cab1b..2f607f41f9d3 100644
--- a/Documentation/devicetree/bindings/iio/dac/ad5758.txt
+++ b/Documentation/devicetree/bindings/iio/dac/ad5758.txt
@@ -50,6 +50,9 @@ Required properties:
 
 Optional properties:
 
+ - reset-gpios : GPIO spec for the RESET pin. If specified, it will be
+		 asserted during driver probe.
+
  - adi,dc-dc-ilim-microamp: The dc-to-dc converter current limit
 		   The following values are currently supported [uA]:
 			* 150000
@@ -71,6 +74,8 @@ AD5758 Example:
 		spi-max-frequency = <1000000>;
 		spi-cpha;
 
+		reset-gpios = <&gpio 22 0>;
+
 		adi,dc-dc-mode = <2>;
 		adi,range-microvolt = <0 10000000>;
 		adi,dc-dc-ilim-microamp = <200000>;